The investigators propose to describe the impact of exposure to higher levels of fluoride from community drinking water supplies on fractures and bone mineral density (BMD). This study is an extension of the only community-based longitudinal study of bone mass having previously characterized BMD and fracture in 1983/4 and 1988/9. This study is unique in its setting which are three communities whose mineral level of fluoride (up to 4 ppm) and elemental calcium (up to 375 mg/l) in the drinking water supply provides a natural experiment in the mineral supplementation. The aim is to determine if fluoride in a community water supplies at 4 ppm is deleterious to bone health; specifically: do higher fluoride levels in community water supplies result in increased fracture risk, rate of BMD change or more bone paint; is higher fluoride exposure related to "bone borrowing" or selective deposition of mineral in trabecular vs. cortical bone; if mineral is selectively deposited, then how is this related to menopausal status, gender, rate of BMD change and degree of fluoride exposure; and are levels of bone turnover markers similar irrespective of fluoride exposure by menopausal status? In 1993/94 and 1996/97, respectively, the investigators propose to re-measure BMD at four anatomic sites (radius, proximal femur, lumbar spine, and total body skeleton) in the existing cohort and in additional men and women from the three communities. BMD will be measured with single energy and dual x-ray densitometry. In the five-year period 1993-98, they propose a fracture surveillance program to abstract data about current fractures; they will also abstract historical medical records from fractures of participants occurring from 1983 to 1993. Participants will be interviewed in 1993/94 and 1996/97 about pain, diet, physical activity, medications, illnesses, use of medications, and indices of fluoride exposure. Additionally, blood and urine will be collected and assayed for fluoride levels and markers of bone turnover. The investigators propose to enrich the existing population of 827 women, recruited at baseline in 1983/84, with current community residents who are between 18-90 years, regardless of residence duration. They anticipate studying more than 1200 women. To this, they will add 40 men from each community for a total estimated sample of 1,320 persons.